Income payments from your SIPP are subject to PAYE Income Tax. If you make a large withdrawal this could push you into a higher tax bracket.
The first time you access your SIPP, we'll need to apply to HMRC for a tax code to make sure we're making the correct deductions. If you have a P45 please forward us parts 2 and 3 of the original document. Until we receive HMRC confirmation or your P45 we are required by law to tax any income paid using an emergency code.